gsm_control_modem(9)

✨ gsm_control_modem(9) ✨

okay so bestie, we're in the Kernel API Manual today and this page is all about gsm_control_modem — that's our little function. let's get into it 💅

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🎀 NAME 🎀

gsm_control_modem — modem status received 💌

like, the modem literally slid into our DMs. that's the whole function. iconic.

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🌸 SYNOPSIS 🌸

void gsm_control_modem (struct gsm_mux *gsm , const u8 *data , int clen );

no return value, no drama, just vibes and three arguments 🫶

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🦋 ARGUMENTS 🦋

• gsm — the GSM channel 💜 this is the mux we're working with, our main character.
• data — data following command 🌈 the actual payload bytes that came after the command byte.
• clen — command length ⭐ how many bytes we're dealing with here.

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💖 DESCRIPTION 💖

okay so picture this: we have received a modem status control message 😭 that's the situation. and this thing is used by the GSM mux protocol to pass virtual modem line status — and optionally to indicate break signals 🔥

so what we do is: unpack it, convert to Linux representation, and — if need be — stuff a break message down the tty 💅 that's it. that's the job. no cap.

ngl the "if need be" is doing a lot of heavy lifting there, so like… pay attention to it 🫶 the break-message stuffing is conditional, not automatic.

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🧚 SEE ALSO 🧚

first up, the kernel file itself, bestie — go read it, it's right here: ./drivers/tty/n_gsm.c 📖

and now the extended friend group, because this function does not travel alone 💀 (all (9) manual pages, obviously):

• fcs / ea / encode girlies: gsm_fcs_add(9), gsm_fcs_add_block(9), gsm_read_ea(9), gsm_read_ea_val(9), gsm_encode_modem(9), gsm_encode_params(9)
• device registry besties: gsm_register_devices(9), gsm_unregister_devices(9)
• packet + frame squad: gsm_print_packet(9), gsm_stuff_frame(9), gsm_send(9), gsm_data_alloc(9), gsm_send_packet(9), gsm_is_flow_ctrl_msg(9)
• queue / kick crew: gsm_dlci_clear_queues(9), gsm_data_kick(9), __gsm_data_queue(9), gsm_data_queue(9), gsm_dlci_data_sweep(9), gsm_dlci_data_kick(9), gsm_kick_timer(9)
• response + command duo: gsm_response(9), gsm_command(9)
• dlci data output crew: gsm_dlci_data_output(9), gsm_dlci_data_output_framed(9), gsm_dlci_modem_output(9)
• control message family: gsm_control_command(9), gsm_control_reply(9), gsm_control_negotiation(9), gsm_control_rls(9), gsm_control_message(9), gsm_control_response(9), gsm_control_keep_alive(9), gsm_control_transmit(9), gsm_control_retransmit(9), gsm_control_send(9), gsm_control_wait(9)
• modem + negotiation processors: gsm_process_modem(9), gsm_process_negotiation(9)
• dlci lifecycle squad: gsm_dlci_close(9), gsm_dlci_open(9), gsm_dlci_negotiate(9), gsm_dlci_t1(9), gsm_dlci_begin_open(9), gsm_dlci_set_opening(9), gsm_dlci_set_wait_config(9), gsm_dlci_begin_close(9), gsm_dlci_data(9), gsm_dlci_command(9), gsm_dlci_config(9), gsm_dlci_copy_config_values(9), gsm_dlci_alloc(9), gsm_dlci_free(9), gsm_dlci_release(9)
• receive state checkers, our hyper-vigilant icons: gsm0_receive_state_check_and_fix(9), gsm0_receive(9), gsm1_receive_state_check_and_fix(9), gsm1_receive(9)
• queue + error + mux management: gsm_queue(9), gsm_error(9), gsm_cleanup_mux(9), gsm_activate_mux(9), gsm_free_mux(9), gsm_free_muxr(9), gsm_alloc_mux(9)
• the gsmld collective: gsmld_output(9), gsmld_write_trigger(9), gsmld_write_task(9), gsmld_attach_gsm(9), gsmld_detach_gsm(9), gsmld_flush_buffer(9), gsmld_close(9), gsmld_open(9), gsmld_write_wakeup(9), gsmld_read(9), gsmld_write(9), gsmld_poll(9)
• modem update crew, our direct coworkers basically: gsm_modem_upd_via_data(9), gsm_modem_upd_via_msc(9), gsm_modem_update(9), gsm_wait_modem_change(9)

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that's the whole page, bestie 💜 you ate that. this one lives over in ./drivers/tty, dated October 2026, and it's filed under gsm_control_modem(9) — slay, go read the source, periodt 🎀✨🦋🌸